I have ben using the terms "feral folk" and "folk in the wild" for some years. Not for any genre particularly, just to describe folk music in its original setting before collectors and revivalists got their hands on it, and started modifying it to suit the new environments it was moved to. In the 20's and 30's in Britain the new environments tended to be associated with classical music, as people like Vaughan Williams(early on) and Benjamin Britten()later) adapted folk songs and tunes for classical style performance. Later, in the 50's, people like Ewan McColl and Lonnie Donegan started popularising modern ways of doing the old songs, and this ended up(in Britain) focussed on the widespread setting up of folk clubs, followed by loads of folk festivals. However, in parallel to these various new ways of doing the old songs, folk music continued to exist(though often only marginally) in its natural habitat, where intrepid enthusiasts could go and seek it out. Rafflesbear is performing a useful public service by pointing out that folk music can be found being performed in venues outside the domesticated world of folk clubs and festivals, and he is using the term "feral folk" to describe this. The term seems very appropriate to describe this, but it must be recognised that other people are using the term to describe their own bands, or a particular genre of modern folk-related music.
So "feral folk", like the word "folk" itself, can refer to more than one thing!